const fp = require('lodash/fp')
const cars = [
    {name: 'Ferrari FF', horsepower: 660,
    dollar_value: 700000, in_stock: true},
    {name: 'Spyker C12 Zagato', horsepower: 650,
    dollar_value: 648000, in_stock: false},
    {name: 'Jaguar XKR-S', horsepower: 550,
    dollar_value: 132000, in_stock: false},
    {name: 'Audi R8', horsepower: 525,
    dollar_value: 114200, in_stock: false},
    {name: 'Aston Martin One-77', horsepower: 750,
    dollar_value: 1850000, in_stock: true},
    {name: 'Aston Martin One-77', horsepower: 750,
    dollar_value: 1850000, in_stock: true}];

// 练习1
let isLastInStock = fp.flowRight(fp.prop("in_stock"), fp.last)(cars)

// 练习2
let firstName = fp.flowRight(fp.prop("name"), fp.first)(cars)

// 练习3
let _average = function (xs) {
    return fp.reduce(fp.add, 0, xs) / xs.length
}
let averageDollarValue = fp.flowRight(_average, fp.map(car => car.dollar_value))

// 练习4
// let _underscore = fp.replace(/\W+/g, '_'); 
let _underscore = fp.replace(/\s+/g, '_')
let sanitizeNames = fp.flowRight(_underscore, fp.lowerCase)
let carsName = fp.map(car => sanitizeNames(car.name))